Question

2. A chestnut trotter was test crossed. All of the offspring were chestnut trotters.Give the probable genotypes of all individuals

Answer 1

Dominant phenotype in all offspring resulting from test cross indicates the the parent with dominant phenotype is homozygous.
Thus, the test-crossed chestnut trotter had genotype TT, the organism, with which it was crossed had genotype tt, and their offspring were all Tt.